json - jackson serialization for Java object with Map? -

i have java class , want convert json using jackson. help.

1. java class

   public class myclass {    string id;    map<string, object> optionaldata = new linkedhashmap<string, object>(); } 

2. how serialization json using jackson objectmapper ?

for example, suppose optionaldata map saving 2 entries <"type", "book"> , <"year", "2014"> want output follow. please note key/value of optionaldata changed on fly (so, cannot create "static" java object without using map)

  [      {        id: "book-id1",       type: "book",       year: "2014"     },     {        id: "book-id2",       type: "book",       year: "2013"      }   ] 

you need write own jackson jsonserializer create custom json string java object per need.

here nice posts along example

• json serializer & deserializerhow use custom serializer jackson?

• how write jackson json serializer & deserializer?

---

the same thing can achieve using gson jsonserializer

here examples

• serialize java object gson

• gson serialiser example - javacreed

---

here code using gson serialiser

list<myclass> list = new arraylist<myclass>();  myclass myclass1 = new myclass(); myclass1.setid("book-id1"); myclass1.getoptionaldata().put("type", "book"); myclass1.getoptionaldata().put("year", "2014"); list.add(myclass1);  myclass myclass2 = new myclass(); myclass2.setid("book-id2"); myclass2.getoptionaldata().put("type", "book"); myclass2.getoptionaldata().put("year", "2013"); list.add(myclass2);  class myclassserialiser implements jsonserializer<myclass> {      @override     public jsonelement serialize(final myclass obj, final type typeofsrc,             final jsonserializationcontext context) {         final jsonobject jsonobject = new jsonobject();          jsonobject.addproperty("id", obj.getid());         map<string, string> optioanldata = obj.getoptionaldata();         if (optioanldata.size() > 0) {             (map.entry<string, string> entry : optioanldata.entryset()) {                 jsonobject.addproperty(entry.getkey(), entry.getvalue());             }         }          return jsonobject;     } }  string jsonstring = new gsonbuilder().setprettyprinting().         .registertypeadapter(myclass.class, new myclassserialiser()).create()         .tojson(list);  system.out.println(jsonstring); 

output:

[     {         "id": "book-id1",         "type": "book",         "year": "2014"     },     {         "id": "book-id2",         "type": "book",         "year": "2013"     } ]